Refrigeration



Aug. 3, 1943. KITTQ I 2,325,778

REFRIGERATION Filed Sept. 8, 1941 INVENTOR William filfilto BY ATTORNEYS5 Patented Aug. 3, 1943 Hoover Company, North Canton,()hio, acorporation of Ohio 7 Application SeptemberS, 1941, SeriaI'NO. 499,924!I Q 19 Claims. ((11.62-1195) This invention relates to refrigeration andmore particularly toian absorption refrigerating apparatus of thepressure equalized type which .is mounted on top of a domesticrefrigerator cabinet so that the evaporator extends downwardly intothe-interior of the cabinet and the absorber and generator are mounted,on the top wall of the cabinet and in which the refrigerating apparatusisremovable from the cabinet as a unit. a 1

In absorption refrigerating apparatus, of the pressureequalized typeusing a refrigerant and an absorption solution, some of the solutionvapor is inevitably driven off in the generator along with therefrigerant vapor, is condensed and led to the evaporator with theliquid refrigerant.

the startof another operating period.

Unless some means is'pr'ovided for purging the,

evaporator of this condensed solution the evaporator will eventuallybecome filled with the solution-or a weak mixture of solution and.refrigerant and as a consequence refrigeration will cease.

In the case in which the solution circuit is 100-. siti'oned below theevaporator this is a compara tivel simple problem since the solution inthe evaporator can be drained to the solution circuit through aliquidtrap or otherwise.

However, where the solution circuit is posi-j tioned above theevaporator the collection of condensed solution in the evaporator offersa more serious problem.

According to this invention the inertg as is placed under pressure inthe inert gas-circuit which includes the evaporatorand theabsorberj andthis inert gas at its raised pressure is utilized to remove thecondensed solution from the evap-' orator which is positioned below thesolution circuit;

theeva porato'r; This liquid which includes liquid, refrigerant and somecondensed solution is liable! to block the lower passage of theevaporator According to another feature of this invention a portion-ofthe inert gas at its raised pressure is utilized to operate a gas lift.pump to purge the evaporator of any liquid contained'therein at thestart ofeach operating period.

Other objects and advantages of this invention will beoo me apparent' asthe description proceeds when taken in connection withthe accompanyingdrawing in which the single figure represents therefrigerating apparatusaccording to this. invention mounted on the top of a domes ticrefrigerator cabinet.

" Referring to the drawing,.thereis-disclosed a three-fluidabsorption'refrigerating system comprising a boiler B, an analyzer D, anair-cooled rectifier R, a tubular air-cooled inclined condenser C, anevaporator E, a gas heat exchanger H; a tubular air-cooled absorber A, asolution reservoir Sfa liquid heat exchanger L, and a circulating fan Fwhich is driven by an electrical motor: M. The abovefdescribed elementsare interconnected by various conduits to form a plural- Further,according to this invention, the evapf orator is so constructed andrelated to the inert gas circuit in such manner that the inert gas' atits raised pressure will blow the liquid in the evaporator including thecondensed refrigerant and solution upwardly through the evaporator.During the process the liquid reitigerantwill evaporate to producerefrigeration andthe condensed solution willbe brought back into thesolution circuit. 7 y

In a refrigerating apparatus of the'type having. an evaporator in whichthe. liquid is blown upwardly therethrough'andfin which the a'ppa ratusis operated intermittently. in accordance refrigeration demand, there isalways some liquid in the evaporator at'thexend of an operating, period.This liquid will fiowdownwardly 'throughLthe evaporatorcoils to thebottornof ity of'gasand liquid circuits constituting a comv pleterefrigerating system to which reference will be madein more'. detailhereinafter.

The refrigerating system will be charged with a suitable refrigerant,such asammonia, a suitable absorbent, such as water, and'asuitable in-'ert pressure 'equalizingmedium, such "asnitrogen. Thejboiler Bwillbe'heated inany suitable man her as by anelectric cartridge heater or byagas burner, as may be desired.

' I The applicationof heat to the boiler liber ates refrigerant vaporfrom-the strong solution contained therein, .The vapor so liberatedpasses upwardly through the analyzer'D in counterflow relationshipto astrong solution flowing down:

wardlythrough the analyzer. .Further refrig-' erant vapor is generatedin the analyzer by theheat .of condensation of absorption solutionvaporgenerated in the boiler.

Some of the solution vapor isgalsoinevitably liberated in the boiler -Balong with-the refrigerant vapor. This solution vapor along with v V therefrigerant vapor is conductedfrom the upper portion of the analyzer Dtothe upper portion of the condenser C through a conduit lit whichincludes the air-cooled rectifier R. where- 'in a portion of theabsorption solution Vapor whichleaves the analyzer is.,condensed and.re-

turned'to the analyzer through the. conduit I3,

The refrigerant vapor and the remainder of the solution vapor isliquefied in the condenser by heat exchange relation with atmosphericair and is discharged from the bottom portion thereof through a conduit15. The bottcm portion of the conduit 55 connects with the bottomportion of an upwardly extending conduit I! through a U-bend 1 8. Theconduit l'i opens at its upper end into'the lower coil of the evaporatorE and discharges thereinto in a manner to be more fully describedhereinafter. The U-bend I8 is provided for the purpose of creating aliquid trap and preventing the gas under pressure in the bottorn coil ofthe evaporator from being blown back through the conduit 15 into thecondenser C as will later become apparent.

The weak solution formed in the boiler B supplied to the evaporatorenters the same simultaneously with the pressure equalizing medium whichis placed under pressure by the circulating fan F. The conduits formingthe entire evaporator are relatively small whereby the pressureequalizing medium flows through such evaporator conduits with arelatively high velocity. The rapidly flowing pressure equalizing mediumsweeps or dragsthe liquid refrigerant along the serpentine coil of thebottom bank 37 thence upwardly through the .lower multi-stage liftconduit 38, along the serpentine coil forming the intermediate bank 31,upwardly through the "upper multi-stage lift conduit 33, along the serbythe generation of refrigerant vapor therefrom m is conveyed from theboiler through a conduit 2|, the outer pass of liquid heat exchanger L,an air cooled pre-cooler 22 and a conduit 23 into the solution reservoirS. The weak solution is conveyed from the solution reservoir S through a.U-shaped conduit 24 which opens into a gas lift pump 25 which in turndischarges into the upper portion of the absorberA. The top of theabsorber A is materially above the solution level normally prevailing inthe boiler-analyzer reservoir system whereby some means'must be providedto elevate the absorption solution into the top of 'the absorber A. Forthis purpose a small bleed conduit 21 communicates with condu'it 25which is connected to the discharge conduit 28 of the circulating fan F.The bleed conduit 2! opens into the gas lift pump 25 below the solutionlevel normally prevailing in the reservoir whereby the weak solutionis-elevated into the top of the absorber by gas lift action.

In the absorber, the weak solution flows downwardly by gravity in.counterflow relationship to the rich pressure equalizing mediumrefrigerant vapor mixture flowing upwardly therethrough'. Therefrigerant vapor content of the mixture is absorbed in the absorptionsolution and theheat of absorption isconducted to the. surrounding airby air cooling fins which are mounted on'the exterior of the absorbervessel.

The strong solution formed in the absorber flows into a conduit 32 whichopensinto the inner passof the heat exchanger L- From the inner pass oftheliqmd heatexchangerL, the strong solution'is conveyed to the upperportion of, the

analyzerD by a strong solution return pipe 33.

The'lea-n pressurejequalizmg medium refrigerant vapor mixture formed inthe absorber A is taken from the upper portion thereof through theconduit 35 into the suction side of the circulating fan F in which it isplaced under pressure and discharged through the conduit 28 into.

theouter pass of the gas heat exchanger H. The pressure equalizingmedium under pressure is conveyed from the outer pass of the gas'heatexchanger through adownwardly extending conduit 35 into the bottomportion of the evaporator E.

The conduit 57 opens into the bottom portion of the conduit 3Swherebythe liquid refrigerant 'pentine coil forming the upper bank 31, up-

wardly through the lift conduit 3? and then horizontally through theserpentine coil'fcrming the box cooling coil 4! as the liquidrefrigerant is diffusing into the inert pressure equalizing medium toproduce refrigeration.

.A s'previously stated, the liquid-supplied to the bottom of theevaporator E is a mixture of liquid refrigerant and condensed absorptionsolution. The inerjt gassupplied to conduit 36 is comparativelywarm andi weak in refrigerant vapor.

It is therefore capable of taking up considerablev refrigerant'vapor asit enter the evaporator E. That being the case a rapid diffusion ofrefrigerant vapor into the inert gas will take place "in the serpentinebanks 37 and the multi-stage lift conduits 38 with the result that theice freezing portion of the evaporator will become extremely tively slowrate with the result that the temperature of the coil 49. will beconsiderably higher than'that of the ice freezing portion of theevaporator E.

By the time the inert gas and remaining liquid. leave the coil 46 therewill be very little or no liquid refrigerant remaining but there willbea slight amount of condensed solution since the solution evaporates at ahigher temperature than the refrigerant. The rapidly flowing richpressure equalizing medium refrigerant vapor mixture leaving the coil.48' sweeps the remaining liquid with it through the'conduit 45, theinner pass of the gas heat exchanger H and conduit 46 into the bottom ofthe absorber A whereby the liquid unevaporated'in'the evaporator Eis'returned to the solution circuit. In the absorber A, the richpressure equalizing medium refrigerant vapor mixture flows upwardly incounterflow to absorptionsolution which absorbs the refrigerant contentof the mixture.

The pressure equalizing medium which enters the evaporator by conduit 36is under pressure and to prevent this pressure from being blown backthrough conduit [5 tothe condenser the U-conduit I8 which connects theconduits l l and I5 is provided to form a liquid trap.

Refrigerating systems are usually operated intermittently in accordancewith refrigeration de-' mand. At the termination of an operating periodthe liquid in the conduit 45, the. inner pass of gas heat exchanger H,conduit 45, coil 40 and the ice freezing portion of the evaporator Ewill flow downwardly into the bottom bank 31 of the evaporator.

bottom bank 3'! of the evaporator by this liquid In order topreventblocking of the 1 aidrainlconduitifl .is providedzwhich .opens into the.topof the coil so that itawillhotfcompletely drain the bottom bank. Thedrainconduit. is connected bya :u-s'hape'dlconduit 148 to agas lift pumpis :of smalladiameter which opens into the top; of the reservoir "S.above the solutionlevel therein. .In orderto supplylmotive' powerto thegas lift pump 48 a small bleed conduit 50-leads to the junction of theconduit 26 with conduit 21.

Since the conduit:ZB'iscQnnectedto the discharge:

finscan be bonded to the top ofthelcasing-=5ll=to facilitate this heat'transfer. I I The conduits 36; 51) :and 9 :areat the rearof theevaporator E so that. ice trays can be the reservoir Sand clear theblockage of the bot tom bank 31 of the evaporatorso that thecircula tionof liquid: refrigerant. and the inert gas through the evaporator willtake place asprevi ously described. Thus any condensedabsorptionsolution which may accumulate in the evaporator E will beremoved even though'it is not blown upwardly through the gas heatexchanger H by'the rapidly flowing inertgas. The liquid trap formed inthe U-shaped conduit 48 will prevent the gas under pressure supplied byconduit lill from being blown upwardly into the evaporator. E.

The solution reservoir Sis vented through a conduit 5! into the suctionconduit of the circulating fan. The-discharge conduit 15 of thecondenser is vented'by a ventconduit 52 'intoithe reservoir S above thesolution level therein. Since the reservoir is connected by conduit 5|to thesuction side of the fan F, the discharge- .conduit- 15 of thecondenser will also beat suetion pressure.

The refrigerating apparatus just described is mounted upon aremovableinsulated panel 53 forming a top closure for a domesticrefrigerator cabinet. The generator B, condenser-C, absorber A motor M,fan F'and their-connecting conduits are mounted upon a suitableframework generally indicated at 54which is mounted on top- The:evaporator E is of the insulated panel 53. supported by its connectingconduits below the insulated panel 53 so as to project into the interiorof the food storage compartment of the remetallic side panels-of thecabinet areextended upwardly and-provided with louvred openings 55 forthe ingress of cooling air.

of cooling air. The entire unit including theinsulated panel 53' can bemoved bodily upwardly when the cover 56 is removed either for servicing;

or replacement. V

The ice freezing portion of the evaporatonE is covered with anornamental casing '51 to hide the evaporator coils and to confine therefrigeration taking placetherein toireezing ice. The two bottom banks3'! of the evaporator form sup ports for ice tray shelves while'the'topbank 3fl is. in thermal contact with the top of the casing, 57 so thatrefrigeration takingplace therein can. be utilized-for-box coolingpurposes. If desired..-

liquid level in the generator or A removable cover 55 is mounted. on topof the-upwardly extending walls and is provided'with openings for theegress.

readily placed upomand removed .from their sup porting shelvesx J Whenthe liquid: is removed from the lower bank 3.? bythe vapor. lift conduit49 a continuous circulation'of inert gas through the conduits andtfliwill takeplacavbut since these conduits are of'veiysmalldiameter theflow willbe small and will notsinterfere with the proper circulationattire-remaining fluids in the apparatus.

From--;=the foregoing it can be seen that this invention provides anabsorption refrigerating:

apparatus of the pressure equalized type in which the evaporator.isvpositioned below the solution circuitand' the inertgas at araisedpressure is utilized to nirculate-"the absorption solutionbetweenthe-bciler and absorber and'to'raise the liquid refrigerantupwardly through the evaporator as well as. to purge the evaporator ofany liquid accumulated'thereinat the start of each operating. period. T7

While I have shown but 'a' single embodiment of my invention it istobe'understood that this embodiment has be taken as illustrative only.andnot in a limiting sense. Ido not wish to be limited tothe specificstructure shown and described but to-include all equivalent variationsthereof: except claims.

I claim-z a interior of said c-abinet below said absorber and condenser,an inert gascircuit, including said evaporator and absorber, means forplacing an inert gas in said circuit undera raised pressure and meansfor leading the liquid refrigerant from said condenser to the lower end'oi'said' evaporator,.said evaporatorand circuit being so; constructedand-arranged that the gas at itsraised pressure will blow liquidrefrigerant up v-" oughsaid evaporator.

2.- An absorption; refrigerating apparatus com a l prising'a condenser,anabsorber, a verticallyexg tending evaporator below said condenser andabsorber, an inert circuit'including said abso rber' andevaporator, aninert gas'in said cir-" cult; means for placing said gas under a raisedpressure and means for leading liquid refrig-v erant from said condenserto the lower' end of said evaporator, said evaporator and'circuitbeingso constructed andarranged' that said gas' at' its raised pressure willblow Jquid'refrigerant upwardly through said evaporator "3. Anabsorption.refrigerating apparatus com}: prising a condenser, anabsorber, a vertically eX, tending evaporator below'said condenser andab sorber; an'inert gas circuit includirigsaidab:

sorber and'evaporatonan inert gas in said circuit; means for placingsaid gas under a raised j pressure; means for leading condensedjrefrig';erantj from" said condenser to the lower end ,of saidevaporator; saidevaporator and circuit be; ing'sdchnstructedand arranged thatfsaid'gasfat'itsraised'pressure will blow liquid refrigerant. upwardly t-hrouglo'said evaporator and means. for utilizing a portion of said gas atits-raised re u r pu si ssa deva tenasliinitedby the scope of theprisinga condenser, an absorber; a vertically extending evaporator below saidcondenser and absorber, an inert .gas circuit including said absorberand evaporator, means for .placing inert gas in said circuit under araised pressure and means for utilizing a portion of said gas at itsraisedpressure for purging said evaporator of condenser, an inert gascircuit including said evaporator and absorber, means for placing aninert gas in said circuit under a' raised pressure and means for leadingliquid refrigerant from said condenser to the lower end of saideVaporator, said evaporator and circuit being so constructedand arrangedthat the-gas at its raised pressure will blow' liquid refrigerantupwardly through said evaporator, said unit being removable from saidcabinet as a unit. a

6. An absorption refrigerating apparatus comprising a generator, acondenser abovesaid generator and connected thereto by a vapor conduit,an absorber below said condenser and above said generator, a, verticallyextending evaporator below said condenser and absorbenconduitsconnecting said generator, absorber and evaporator so as to form asolution circuit including said generator andabsorber and an inertgascircuit includingsaid evaporator and absorber, means for placing inertgas in said inert gas circuit under a raised pressure and means forutilizing a portion of the inert gas atits raised pressure for liftingsolution from the bottom of said evaporator into said solution circuit.

7. An absorption refrigerating apparatus comprising a generator, acondenser above said generator and connected thereto by a vapor conduit,an absorber below said condenser and above said generator, a verticallyextending evaporator below said condenser and absorber, conduitsconnecting thegenerator, absorber-and evaporator so as to form asolution circuit including said generator and absorber and an inert gascircuit including said evaporator and absorber, means for placing inertgas in'said .inert gas circuit under a raised pressure, means forleading liquid refrigerant from said condenser to the bottom of saidevaporator and means for utilizing a portion of the inert gas at itsraised pressure for lifting solution from the bottom of said evaporatorinto said solution circuit.

8. An absorptionrefrigerating apparatus comprising a generator, acondenser, above said generator and connected thereto by a vaporconduit,

an absorber below said condenser and above said generator, a verticallyextending evaporator below said condenser and absorber, conduits conenecting said generator, absorber and evaporator so as to form a solutioncircuit including said generator and absorber and an inert gas circuitincluding said evaporator and absorber, means,

for placing inert gas in said inert gas circuit under a raised pressure,means for leading liquid refrigerant from said condenser to the bottomofsaid evaporator, said evaporator and inert 4. An absorptionrefrigerating apparatus com inert gas at its raised pressure for liftingsolution from the bottom 'of said evaporator into said i circuit under araised pressure and means for leading liquid refrigerant from saidcondenser to the bottom of said evaporatonsaid evaporator and. circuitbeing so constructed and arranged that the gas at its raised pressurewill blow liq-.

'; uid refrigerant upwardly through said evaporator.

10. An absorption refrigerating apparatus comprising a generatonacondenser above said generator and connected thereto by a vapor conduit,an absorber below said condenser and above said generator, a verticallyextending evaporator below said condenser and absorber, conduitsconnecting said generator, absorber and evaporator so as to form asolution circuit including said generator and absorber and an inert gascircuit including said evaporator and absorber,means for placing inertgas in said inert gas circuit under a raised pressure and means forutilizing a portioncf the inert gas at its raised pressure for liftingsolution from the bottom of said evaporator into said solution circuit,said iast named means comprising a gas lift pump.

ll. A refrigerator comprising a cabinet having a removable insulated topwall, an absorption,

refrigerating unit mounted onsaid top wall, said unit comprising agenerator, a condenser above I said generator and connected thereto by avapor conduit, an absorber below said condenser and above saidgenerator, an evaporator below said condenser and absorber, saidgenerator, condenser and absorber being mounted on the top of saidinsulated wall and said evaporator extending downwardly into theinterior of said cabinet below said insulated wall, a solution circuitincluding said generator-and absorber, an

inert gas circuit including said evaporator and absorber, -means forleading liquid refrigerant from said condenser to the bottorn of saidevaporator, means in said inert gas circuit for placing 1 inert gastherein under a raised pressure, said inert gas circuit and evaporatorbeing so con-- structed and arranged that inert gas at its raisedpressure will blow liquid refrigerant upwardlythrough said evaporator,means for uti- 1 lizing a portion of said inert gas at its raised'a'tor, an evaporator below said condenser and absorber, said generator,condenser and absorber being mounted on top of said insulated wall andsaid evaporator extending' downwardly. into the interior of said cabinetbelow said insulated wall, a solution circuit including said generatorand absorber, an inert-gas circuit inciudingusaid evaporatorand"absorber; means forul'eading liquid refrigerant from said condenserto the bottom of said evaporator, means in said inert gas circuit forplacing inert gastherein under a raised pressure, said inert gascircuitand evaporator beingso constructed and arranged that the inertgas at itsraised. pressure will blowlli'qui'd refrigerant upwardly through said.evaporator,

gas lift means for utilizing a portion of said inert gasat its raisedpressure for circulatingsos 'lution in said solution circuit and gaslift rneans for utilizing another portion of said inert'gas at itsraised pressure for returning unevaporated solution from the bottom ofsaid evaporator-tosaid solution circuit; l V

13. A refrigerating apparatus comprising a cabineth aving a removableinsulated top wall, an absorption refrigerating unit mounted on saidinsulated top wall, said unit comprising a gen erator, a condenser abovesaid generator and connected thereto by a vapor conduit, an'absorberbelow said condenser and above said" genorator, an evaporator below saidcondenser and absorber, said generator, condenser and absorber beingmounted on top of said insulated wall and said evaporator extendingdownwardly net belowsaid insulated wall, a solution cirinto the interiorof said cabicuit including said generator and absorber, an inert gascircuit including said evaporator and absorber, means for leading liquidrefrigerant from said condenserto the bottom of said evaporator, meansin said inert gas'circuit for placing inert gas therein under a raisedpressure, said inert gas circuit and evaporator being so cons ructed andarranged that the inert'gas at its raised pressure will blow liquidrefrigerant upwardly through said evaporator, means for utilizing 'aportion of said inert gas at its raised pressure for circulatingsolution in said solution circuit and means for utilizing anotherportion of said inert gas at its raised pressure for returningunevaporated solution from the bottom of said evaporator to saidsolutioncircuit, said unit being removable from said cabinet as a unit. 7 I

14;. A refrigerator comprising a cabinet having an insulated top wall,an absorption refrigerating unit mounted on top of said insulated wall,said unit comprising a generator, a condenser above said generator andconnected thereto by a vapor conduit, absorber below said condenser andabove said generator, anevaporator below said condenser and absorber,said generator, condenser and absorber being mounted on top of saidinsulated wall andsaid evaporator extending downwardly intothe interiorof said cabinet below said insulated wall, a solution circuit includingsaid generator and absorber, an inert' gas circuit including saidevaporator and absorber, means for leading liquid refrigerant from saidcondenser to the bottom of said evaporator, means in said inert gascircuit for placing inert gas therein under a raised pressure, saidinert gas circuit and evaporator being so constructed and arranged thatinert gas at its raised pressure will blow liquid refrigerant upwardlyto said evaporator, gas lift means for utilizing a portion of said inertgas at its raised pressure for circulating solution in said'solutioncircuit and gas lift means for utilizing another portion ofsaid a-bove'the normal yliquid level therein.

inert gas? at. itsiraised pressureifor retuming' ungevaporated; solutionfromfltthe bottomiof' said evaporator to said; solution circuit; saidlast-mom tioned =means opening into said. solution 5 ircui t 15'. Arefrigerator com-prising, acabinethaving an-insulated top wall, an'alo'sorption refrigerating apparatus mountedon said insulated wall/saidapparatus-comprisinga generator, a condenser :above said generatorandconnected theretoby vapor c onduits'including Ia rectifier, anabsorber below said condenser and above said generator, an evaporatorbelow said absorber and condenser', said generator, condenser andabsorber being mounted on top-of said insulated wal-l and saidevaporator extending downwardly into-the interior of said cabinet belowsaid insulatedwall, an inert gas circuit including said evaporatonan'dabsorber, meansi'n 'saidinert gas circuit' for placing inert gasth'ereinu-ndena ra i'sed p'res sure, means for leading liquidrefrigerant-fromcrating unit mounted on said insulated wallJsaid unit comprising agenerator, .a'condenser above said generatorfand connected thereto by avapor' conduit, an absorber below said condenserand above. saidgenerator, an evaporator below said 1' said condenser to the bottom ofsaid evaporator,

me ns incl din -a gas lift pump 'for circulatin solution from saidgenerator .tothe top of said absorber and for returning it to saidgenerator by gravity and means for utilizing a portion of said inertgas. forfreturning uneva'porated. solution'from the bottom or saidevaporatorv to said wall and said evaporator extending downwardly intothe interior or said cabinet below said insulated wall, an inert gascircuitincluding said evaporator and absorben'means in said inert gascircuit for placing inert gas therein under a raised pressure, means forleading'liqui dlrefrigerant from said condenser to the bottom of saidevaporator, means including a gas lift pump for I circulating solutionfrom said generator to the" top of said absorber and for returning it tosaid generator by gravity and means forutilizing a portion of said inertgas at its raised pressure for returning unevaporated solution from thebottom of said evaporator to the solution circuit above the normalliquid level therein.

1'7. A refrigerator comprising a cabinet having an insulated top Wall,an absorption refrigabsorber and condenser, said generator, condenser,and absorber being mounted on top of said insulated wall and saidevaporator extending downwardly into the interior of said cabinet belowsaid insulated wall, an inert. gas circuit including'said evaporator andabsorber, means in said inert gas circuit for placing inert gas thereinunder a raised pressure, and means for leading liquid refrigerantfromisaid condenser to the bottom ofsaid evaporator, saidevapor'atorcomprising. a plurality of banks of serpentine tubing connected vbymul-ti-stage riser sections, said inert gas circuit being so arrangedrelative to said evaporator that inert gas at its raised sorber, meansin said inert gas circuit for pl acing inert gas therein .under a raisedpressure and means;for leading liquid refrigerant from said condenser tothe bottom of said evaporator, said -evaporator comprising a, pluralityof banks of serpentine tubing connected by multi-stage riser sections,said inert gas circuit being so'arranged -relativetosaidevaporator thatinert gas at its raisedpressure will sweep liquid refrigerant throughthe banks of; serpentinetubing and upwardly through the riser sectionsas it is evaporating into the inert gas to produce refrigeration. a a

- 19-. An absorption refrigerating apparatus comprising a generator, acondenser above said generator and connected thereto by a vapor'conduitincluding a rectifier, an absorber below said condenser and above saidgenerator, an evaporator below said absorber and condenser, an inert gascircuit including said evaporator and absorber, means in said inert gascircuit for placing inert gas thereinunder a raised pressure,

meansfor leading liquid refrigerant from said condenser to the bottom ofsaid evaporator, a solution circuit including said generatorandabsorber. and means including a gas lift pump for utilizing a portionof the inert gas at. its: raised pressure for returning unevaporatedsolution from the bottom of said evaporator to said solution circuit. rY

- l WILLIAM H. 'KI'ITO.-

